The present invention relates to equipment used in dental applications and, in particular, a handpiece or handpiece accessory for use in endodontic and other dental applications to provide a slow secondary rotary motion to enhance uniformity of results when using a rapidly oscillating tool.
Historically, endodontic devices have been proposed which employ a wide range of up-down oscillating motion, rotary motion and various compound motions. Where more than one mode of motion is provided, the frequency of the different modes of motion are typically similar. For devices operating with a rotary motion, speeds of rotation are typically in excess of about 200 rpm, and in many cases, thousands of rpm.
The present invention relates particularly to a subclass of tools for which the primary motion is a longitudinal reciprocating motion, i.e., along a line corresponding to the length of the tool. One non-limiting but particularly preferred example is the self-adjusting file described in European Patent No. EP 1708638 B1, which is hereby incorporated by reference in its entirety.
During operation of a tool with purely longitudinal reciprocating motion, there is a risk that uneven wear may occur to the tool and/or that a tool that is not rotationally symmetric may result in non-uniform results in the tissue being treated. Certain commercially available handpieces which provide reciprocating motion allow for free rotation of the tool during use, thought to reduce stress in the tool. However, this freedom of rotation does not ensure that rotation will occur during use.
There is therefore a need for a dental tool displacement apparatus handpiece, or an accessory for use with an existing handpiece, which would provide slow rotation of a tool while the tool undergoes relatively higher frequency reciprocating motion, thereby enhancing the uniformity of operation of the tool. It would also be particularly advantageous to provide a compact and effective transmission arrangement which would allow both reciprocating and rotational motions in any desired ratio to be derived from a single drive motor.